Field of the Invention
The present invention relates to optical image anti-shake devices and, more particularly, to an optical image anti-shake device for use with cameras and mobile devices.
Description of the Prior Art
One of the most important challenges facing by persons skilled in the art is to reduce or even eliminate the effect of a shaking camera positioned at a handheld device or a moving carrier (such as an automobile or a flight vehicle) upon pictures of formed images in the course from picture-taking to image-forming.
Optical image anti-shake technique, which is rapidly developing, is regarded as a potential leader of image anti-shake techniques in the years to come. Unlike a digital image anti-shake mechanism, the optical image anti-shake technique has advantages as follows: image-forming quality never deteriorates despite software-based correction; and software-based processing is seldom prolonged.
Due to the development of mobile electronic devices, such as cellular phones and tablets, mini cameras are becoming more popular. Consumers and researchers look forward to enhancing the performance of mini cameras while maintaining their compact appearance, especially applying the optical image anti-shake technique of existing cameras to mini cameras disposed inside mobile electronic apparatuses, such as cellular phones and tablets, and enhancing the performance of the mini cameras.
During a picture-taking process, a conventional optical image anti-shake device compensates for the vibration of cameras with a magnetic force as a result of the induction effectuated by a magnet and a driving coil. Hence, the distribution and stability of the magnetic force in the device is of vital importance.
Japan Published Patent Application 2011-128583 discloses a lens-unit driving device, wherein a magnet retention portion material is capable of enhancing the magnetic efficiency of an autofocus magnet. Although Japan Published Patent Application 2011-128583 discloses preventing the magnetic lines of force of the autofocus magnet from dispersing but does not disclose protecting an anti-shake magnet against the interference from an external magnetically permeable component. As a result, Japan Published Patent Application 2011-128583 has a drawback as follows: if a magnetically permeable component is disposed outside the lens-unit driving device, it will attract the anti-shake magnet and thereby affect the operation of the optical image anti-shake mechanism.
Japan Published Patent Application 2012-113230 discloses an autofocus module with a casing which is capable of enhancing the magnetic efficiency of a magnetic field and located at a fixing portion, wherein a magnet is disposed inside the casing, fixed to the inner periphery of the casing, and located at the fixing portion; hence, even if a magnetically permeable component is disposed outside the autofocus module, it will not affect the autofocus mechanism. However, Japan Published Patent Application 2012-113230 has a drawback, that is, if the internal magnet is located at an active portion, the casing cannot prevent the magnet from attracting an external magnetically permeable component.